As solar energy is predicted to become the leading energy source worldwide by 2050, many investors are looking to market leaders such as First Solar Inc. (FSLR) and SunPower Corp. (SPWR) as long-term plays.

While both companies benefit from government policies that incentivize spending on solar, along with the improved efficiency of solar cells, the firms maintain very different positions within the overall market. (See also: 2017: A Turning Point for the Solar Industry.)

Differences of Scale

Tempe, Ariz.-based First Solar holds strength in the utility scale market, where it provides thin-film solar panels well-suited for harsh environments. The global leader in photovoltaic (PV) energy solutions says it has sold more than 13.5 gigawatts worth of capacity worldwide, primarily in large-scale grid-connected PV power plants.

San Jose, Calif.-based SunPower, on the other hand, boasts the industry’s highest-performing solar systems that target homeowners and businesses. Since 1985, the Silicon Valley tech firm has generated more than 18 million megawatt hours (MWh) of solar energy. While First Solar focuses mainly on utilities, SunPower touts a “diversified global portfolio leading residential, commercial and utility scale energy markets.” While the two firms overlap, they do so with very different products. SunPower’s high-efficiency panels, better for space-constrained spaces, contrast greatly to First Solar’s cost-efficient thin film solutions.

First Solar has seen its stock decline an approximate 51% on a year-over-year (YOY) basis at a price of $31.32 on Wednesday afternoon. Investors fled to the sidelines as the firm announced a restructuring program intended to streamline the production of a more cost-competitive solar panel system module to offset declining solar-panel prices. Shares of SunPower have dropped about 68% over the same period. (See also: The Current State of the Solar Energy Industry.)